Motor generator locomotive



April 9 P, w. FORSBERG 2,036,803

MOTOR GENERATOR LOCOMOTIVE Filed June 15-, 1932 Motonir g Regen enating Inventon: Peben W Fonsberg, 1 W% His Abbonneg.

Patented Apr. 7, 1936 UNITED STATES MOTOR GENERATOR LOCOMOTIVE Peter W. Forsberg, Schenectady, N. Y., assignor to General Electric Company, a corporation of New York Application June 15, 1932, Serial No. 617,398 3 Claims. (01. 172-239) My invention relates to control systems for variable voltagedrives wherein the driving motor is subjected to an overhauling as well as a motoring load, and has for an object the 5 provision of a simple and reliable control of the motor for motoring and regenerative operations.

While my invention has other applications,

it is particularly applicable to a railway locomotivearranged to be operated from either high in voltage A. C. or D. 0. power supply which is transformed to low voltage direct current by means of a motor generator set for the traction motors.

Heretofore, a motor designed for operation at l5 a high voltage has been connected directly across the supply source and has been arranged to drive a load generator. This load generator was connected in a closed circuit with the driving motor to form a variable voltage drive of a 20 well known type. To provide excitation for the motor field windings during regeneration an auxiliary generator has been provided which was only used during the regenerative operation of the motor.

25 In accordance with my invention in one form thereof, I provide an auxiliary generator permanently connected in series with the driving ,motor and the load generator together with means for connecting return circuits, from the 30 series field windings of the motor to the auxiliary generator so that this generator may supply excitation to the motor field windings for regenerative operation.

For a more complete understanding of my 5 invention, reference should now be had to the drawing in which Fig. 1 diagrammatically illustrates my invention as applied to a locomotive. Fig. 2 illustrates the connections completed by the operation of the controller to its first positicn, while Fig. 3 illustrates the connections completed by the controller when operated to its second position for regenerative braking.

Reerring to the drawing, I have shown my invention in one form as applied to the control 45 of the driving motors I and I I, each provided with series field windings I2 and i3. The motors l9 and II are connected in parallel with each other and in series with an auxiliary generator l5 and a load generator it. A high voltage 50 motor 48 is arranged to receive power from the supply conductor 20 by means of the trolley 2 I, a return circuit being provided by the ground connection 22. A separately excited field winding 23 is arranged to provide excitation of the 55 motor H3. The field windings 25 and 26, respectively, provided on the auxiliary generator l5 and the load generator l6 are arranged to be excited by means of connections completed by a master controller 29. A pair of field rheostats 30 and 3| may be used to control the excitation 5 of the field windings 25 and 26. For regenerative operation, a pair of resistances 33 and 34 are arranged to be connected by the master controller 29 to provide return circuits from the series field windings of the motors to and ll 10 to the auxiliary generator'lS.

With the above understanding of the elements and their organization with respect to each other in the system, the operation of the system itself and the manner in which the auxiliary generator l 5 is utilized for both regenerative and motoring operations will be readily understood from the description which follows: In the operation of my invention it will be assumed that the supply lines are energized in accordance with the well understood symbols for direct current. The trolley 20 may be energized from either an alternating or a direct current source of supply. The motor I 6 will be selected for operation on the particular power supply available. If the series motors are to be operated for motoring the circuit controller 29 is operated to its first position for motoring. The connections thereby completed are shown in simplified form in Fig. 2. For the motoring operation it will be observed 30 that the field windings 25 and 26 for the generators l5 and it are connected in series with a single control rheostat 3! to the positive and negative supply lines 4! and 42. With this arrangement the excitation of these generators is jointly controlled by the single rheostat so that each generator will supply its proper proportion of the load for diiferent positions of the rheostat. The generator I 5 is of much smaller capacity than the load generator I 6 although it is designed to carry the full load current of the circuit. The voltageof the generator i5 is selected with reference to regenerative operation. For example, if the series motors l0 and H are arranged to be operated on a voltage of 5' 750 volts and a potential difference of 75 volts is required during regeneration, it will be seen that the generator IE will be designed to generate 75 volts with its armature carrying the full load current of the motors. The load generator is will then be designed to supply power at 675 volts so that the total voltage applied to the motors I 0 and l l during motoring'operation may be 750 volts, corresponding to their rated voltages. I5

If it were not'ior the use of the auxiliary generator I! during the motoring operations, the generatorl6 would have to be designed to supply power at 750 volts. with my arrangement, however, the load generator It may be of less capacity inasmuch as the auxiliary generator will supply a portion of the load. Furthermore,

by maintaining the auxiliary generator IS in series circuit relation with the load generator l8 and the series motors in and II, the switching required in changing from motoring to regenerative braking is greatly simplified.

' For example, if regenerative braking is desired, it is only necessary to operate the controller 29 to its second position thereby establishing the connection shown in Fig. 3. It will be seen that the resistances 33 and 34 are connected in parallel with their corresponding field windings l3 and I2 and across the armature of the auxiliary generator l5. By means of these connections return circuits are provided from the field windings l2 and Hi to the, auxiliary generator so that these windings will produce the necessary excitation for regeneration. Furthermore, the circuits through the resistors 33 and 34 provide return paths for the regener: ative current produced by the motors l0 and H during braking.

In order to control the regenerative braking effort the controller 29 in its second position connects the rheostats 30 and 3! in series with their corresponding field windings 25 and 26 so that the excitation of these field windings may be independently varied to control the braking eflort. While I have shown a particular embodiment oi'my invention, it will be understood 0! course that I do not wish to be limited thereto, since many modifications may be made, and I thereiore contemplate by the appended claims to cover any such modification as fall within the true spirit and. scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is,

1. In an electric driving system including a trolley and a ground connection, the combinatlon of a series motor, a series field winding therefor, an auxiliary generator and a load generator permanently connected in series with each other and with said series motor, field windings for each of said generators. rheostatic means associated with each of said generator field windings, a driving motor for said generators connected between said trolley and said ground, means for connecting said generator field windings in series with each other and with one of said rheostatic means during motoring operation, and means for producing regenerative operation of said series motor comprising an electrical connection lay-passing said motor field winding and said auxiliary generator armature whereby said auxiliary generator supplies excitation for regenerative braking of said series motor. Y

2. A variable voltage drive comprising a load generator, an auxiliary generator, and series motor-means connected in closed circuit relation with said generators, field windings for each of said generators, rheostatic means for each of said field windings, a resistance for each of the series windings of said motor means, and a circuit controller for connecting said generator field windings in series with each other and one of said rheostatic means for motoring, and for connecting said generator field windings in series with their respective rheostatic means, and for connecting each of said motor field resistances in parallel with its respective series winding of said motor-means and said auxiliary generator for regenerating.

3. The combination in a variable voltage drive including a series motor, of a load generator and an auxiliary generator, of means for permanently connecting said motor and said generators in closed circuit relation in each other, field windings for each of said generators, rheostatic means for each of said field windings, means for connecting said generator field windings in series with each other and with one of said rheostatic means to control the speed of operation of said motor, means for producing regenerative operation of said motor comprising an electrical connection by-passing said motor field winding and the armature of said auxiliary generator, and means for controlling the field winding of said load generator independently of the field winding of said auxiliary generator during regenerative operation.

PETER W. FORSBERG.

series with 3 

